Aborting Builds: use different signals

git commands respond well and clean up after SIGINT (ctrl-c)
while our actual command will be sent SIGTERM.
Aborting: kill all children on aborting a build

Previously, killing a bash script *wouldn't* kill its child processes
Now it does, and now we have a test.

Delete the timeout option from execOptions (and use a clone of it).
Pass along stderr from exec() too.
git-build: add require('underscore')
Merge kill-with-sigint (#61) into master

Aborting: kill all children on aborting a build

Previously, killing a bash script *wouldn't* kill its child processes
Now it does, and now we have a test.

Delete the timeout option from execOptions (and use a clone of it).
Pass along stderr from exec() too.

Send SIGINT to abort the git commands.